Part of the pre-Alpine jungle of recorders.
The K-8 isn't a mountain high but a recorder with the standard features of a mid-end 1979 recorder : one motor, one capstan, one 3-layer laminated Sendust r/p head, feather-touch pads, FL display & counter, Bias fine trim pot, Rec Mute switch plus Tiimer & Auto play / rewind / repeat functions.
The record amplifier is Luxman's Realtime Processed DC circuit, as inaugurated in 1976 with the Laboratory Standard Series.
What the K-8 has on top is fine looks, worthy of a Studio Standard Series.
And what is has as well is a little hole in its lid to access the Play Skew adjustment of the Luxman XM tapes : those ultra-rare rarities which allow to separately adjust the tape's playback and record mechanisms.
As for almost everybody else, Alpine may have had a hand in the K-8, at least for the heads, pots and switches. Or partly. Or not.
But the mechanism location, to the regular left, probably denotes a more "common" outsourcing than the 5K50 or K-12 for instance. The K-10 was made by Copal Koki...
And it is quite possible the K-8 had another life, cosmetically different, later on, under another name and another "series" - Luxman is Luxman.